wizard(apple): proper support for ISO disk drives

[ktprograms]

If I download the Alpine Linux 3.15 virt aarch64 ISO and extract the vmlinuz and initramfs from it, I can then use the whole ISO as the rootfs.

This causes a problem because 60ac313 makes it that putting a ISO in the rootfs field will cause a disk image to not be created, which is wrong.

I propose adding a ISO field that will also be marked as read only, since you can't write to an ISO.

(followup to #3461 (comment))

[osy]

The one thing I don't like about this is that it makes the wizard flow more complicated for Linux now. Please test and try to see if any edge cases break the wizard. Thanks.

[ktprograms]

@osy since the current code isn't making it read only anyway, I think the simplest thing to do is to revert this commit and just add a checkbox for Skip creation of disk.

FYI If you do git rebase -i HEAD~2 and in the editor change the word pick to drop on line with 007f9d4, that will remove the commit without creating another revert commit. (you will have to force push after that)

[osy]

8eacd8f now makes it read-only. Is that all?

[ktprograms]

Also a HStack around the Browse and Clear buttons for the Boot ISO Image is needed, thanks

I'll do some proper testing and let you know

[ktprograms]

@osy It's working fine so far, but it seems that 60ac313 doesn't work properly. It skips the disk creation wizard step, but a 64 GB disk is still created.

[osy]

Fixed in ceb6f91